A heating ventilation and air conditioning (HVAC) unit as a unit forming a vehicle air-conditioning device is configured to selectively blow air into a vehicle compartment through any of a face blowing port, a foot blowing port, and a differential blowing port to adjust the temperature of the inside of the vehicle compartment, the air being temperature-adjusted to a set temperature through an evaporator, a heater core, an air mix damper, etc. arranged inside the unit.
In addition to the air mix damper, a plurality of blowing mode switching dampers configured to open/close each blowing port, such as a face/differential damper and a foot damper, are rotatably supported through corresponding damper shafts in the HVAC unit. These dampers are opened/closed through a link mechanism including a link plate rotated by, e.g., a motor actuator with a potentiometer or a stepping motor and a damper lever having a pin slidably fitted in a cam groove provided at the link plate, for example. In this manner, temperature adjustment control or switching of a blowing mode is performed (see, e.g., Patent Citations 1 and 2).
In a damper opening/closing mechanism configured to open/close, as described above, each damper through the link mechanism including the link plate with the cam groove, the damper lever, etc., the pin provided at the damper lever and having a circular cross section is slidably fitted in the cam groove of the link plate. Thus, the cam groove has such a groove width that the pin is fitted with a certain clearance, and an end portion of the cam groove has generally an arc shape with a radius of ½ of the groove width as described in Patent Citations 1 and 2.